// Advent of Code 2018
// December 16, 2018
// Author: Peter Jensen

(function () {
  var fs = require("fs");

  var addr = 0;
  var addi = 1;
  var mulr = 2;
  var muli = 3;
  var banr = 4;
  var bani = 5;
  var borr = 6;
  var bori = 7;
  var setr = 8;
  var seti = 9;
  var gtir = 10;
  var gtri = 11;
  var gtrr = 12;
  var eqir = 13;
  var eqri = 14;
  var eqrr = 15;

  var opcodeMap = [
    addr, addi, mulr, muli, banr, bani, borr, bori, setr, seti, gtir, gtri, gtrr, eqir, eqri, eqrr
  ];

  function parseNumbers(numsStr) {
    var nums = numsStr.split(/[ ,]+/);
    for (var i = 0; i < nums.length; ++i) {
      nums[i] = parseInt(nums[i]);
    }
    return nums;
  }

  function readInput(fileName) {
    var input = fs["readFileSync"](fileName, "utf8");
    var lines = input.split(/[\r\n]+/);
    var index = 0;
    var samples = [];
    var program = [];
    while (index < lines.length) {
      var line = lines[index];
      if (line.substr(0, 6) == "Before") {
        var before = parseNumbers(line.substr(9, 10));
        var opcode = parseNumbers(lines[index+1]);
        var after  = parseNumbers(lines[index+2].substr(9, 10));
        samples.push({before: before, opcode: opcode, after: after});
        index = index + 3;
      }
      else {
        program.push(parseNumbers(lines[index]));
        index++;
      }
    }
    return [samples, program];
  }

  function execute(opcode, input) {
    var output = input.slice(0);
    switch (opcodeMap[opcode[0]]) {
      case addr:
        var A = input[opcode[1]];
        var B = input[opcode[2]];
        output[opcode[3]] = A + B;
        break;
      case addi:
        var A = input[opcode[1]];
        var B = opcode[2];
        output[opcode[3]] = A + B;
        break;
      case mulr:
        var A = input[opcode[1]];
        var B = input[opcode[2]];
        output[opcode[3]] = A * B;
        break;
      case muli:
        var A = input[opcode[1]];
        var B = opcode[2];
        output[opcode[3]] = A * B;
        break;
      case banr:
        var A = input[opcode[1]];
        var B = input[opcode[2]];
        output[opcode[3]] = A & B;
        break;
      case bani:
        var A = input[opcode[1]];
        var B = opcode[2];
        output[opcode[3]] = A & B;
        break;
      case borr:
        var A = input[opcode[1]];
        var B = input[opcode[2]];
        output[opcode[3]] = A | B;
        break;
      case bori:
        var A = input[opcode[1]];
        var B = opcode[2];
        output[opcode[3]] = A | B;
        break;
      case setr:
        var A = input[opcode[1]];
        output[opcode[3]] = A;
        break;
      case seti:
        var A = opcode[1];
        output[opcode[3]] = A;
        break;
      case gtir:
        var A = opcode[1];
        var B = input[opcode[2]];
        output[opcode[3]] = A > B ? 1 : 0;
        break;
      case gtri:
        var A = input[opcode[1]];
        var B = opcode[2];
        output[opcode[3]] = A > B ? 1 : 0;
        break;
      case gtrr:
        var A = input[opcode[1]];
        var B = input[opcode[2]];
        output[opcode[3]] = A > B ? 1 : 0;
        break;
      case eqir:
        var A = opcode[1];
        var B = input[opcode[2]];
        output[opcode[3]] = A == B ? 1 : 0;
        break;
      case eqri:
        var A = input[opcode[1]];
        var B = opcode[2];
        output[opcode[3]] = A == B ? 1 : 0;
        break;
      case eqrr:
        var A = input[opcode[1]];
        var B = input[opcode[2]];
        output[opcode[3]] = A == B ? 1 : 0;
        break;
    }
    return output;
  }

  function numOpcodes(sample) {
    var n = 0;
    var opcode = sample.opcode.slice(0);
    for (var opIndex = 0; opIndex < opcodeMap.length; ++opIndex) {
      opcode[0] = opcodeMap[opIndex];
      var v = execute(opcode, sample.before);
      if (v[opcode[3]] == sample.after[opcode[3]]) {
        n++;
      }
    }
    return n;
  }

  function getPossibilities(sample) {
    var p = [];
    var opcode = sample.opcode.slice(0);
    for (var opIndex = 0; opIndex < opcodeMap.length; ++opIndex) {
      opcode[0] = opcodeMap[opIndex];
      var v = execute(opcode, sample.before);
      if (v[opcode[3]] == sample.after[opcode[3]]) {
        p.push(opcode[0]);
      }
    }
    return p;
  }

  function filterPossibilities(possibilities, p) {
    return possibilities.filter(function (val) {return p.indexOf(val) != -1;})
  }

  function findOpcodePossibilities(op, samples) {
    var possibilities = [];
    for (var i = 0; i < samples.length; ++i) {
      if (samples[i].opcode[0] == op) {
        var p = getPossibilities(samples[i]);
        if (possibilities.length == 0) {
          possibilities = p.slice(0);
        }
        else {
          possibilities = filterPossibilities(possibilities, p);
        }
      }
    }
    return possibilities;
  }

  function removeFrom(value, pMap) {
    var removed = false;
    for (var i = 0; i < pMap.length; ++i) {
      if (pMap[i].length > 1) {
        var e = pMap[i].indexOf(value);
        if (e != -1) {
          pMap[i].splice(e, 1);
          removed = true;
        }
      }
    }
    return removed;
  }

  function trimMap(pMap) {
    var trimming = true;
    while (trimming) {
      trimming = false;
      for (var i = 0; i < pMap.length; ++i) {
        if (pMap[i].length == 1) {
          if (removeFrom(pMap[i][0], pMap)) {
            trimming = true;
          }
        }
      }
    }
  }

  function updateOpcodeMap(pMap) {
    for (var i = 0; i < pMap.length; ++i) {
      opcodeMap[i] = pMap[i][0];
    }
  }

  function executeProgram(program, registers) {
    for (var i = 0; i < program.length; ++i) {
      registers = execute(program[i], registers);
    }
    return registers;
  }

  function main() {
    var input = readInput(process["argv"][2]);
    var samples = input[0];
    var program = input[1];
//    console.log("Samples: " + samples.length);
//    console.log("Program: ");
//    console.log(program);
    var threeOrMore = 0;
    for (var i = 0; i < samples.length; ++i) {
      var n = numOpcodes(samples[i]);
      if (n >= 3) {
        threeOrMore++;
      }
    }
    console.log("Three or More: " + threeOrMore);
    var pMap = [];
    for (var op = 0; op < opcodeMap.length; ++op) {
      var  p = findOpcodePossibilities(op, samples);
      pMap.push(p);
    }
//    console.log("Before trimming:");
//    console.log(pMap);
    trimMap(pMap);
//    console.log("After trimming:");
//    console.log(pMap);
    updateOpcodeMap(pMap);
//    console.log("Executing Program:");
    var registers = executeProgram(program, [0, 0, 0, 0]);
//    console.log(registers);
    console.log("Register 0 after program execution: " + registers[0]);
  }

  function test() {
    var sample = {before: [3, 2, 1, 1], opcode: [9, 2, 1, 2], after: [3, 2, 2, 1]}
    console.log(numOpcodes(sample));
  }

  main();
  //test();
})();